1. Field of Invention
This invention relates to static structures, and more particularly to an improved modular system for mounting and supporting continuous thermal insulation and exterior cladding on a structure while providing a rain screen between the continuous thermal insulation and the exterior cladding, providing a for vertical and horizontal re-plumbing of exterior cladding and eliminating thermal conductivity from the exterior of the structure to the interior of the structure, and visa-versa.
2. Background and Description of Prior Art
It is well known in the construction field to build structure walls with plural spaced apart parallel vertical studs of wood or metal. The studs communicate, at a bottom end portion with a wall plate that is anchored to a lower support which may be a building foundation, and at an upper end portion with a ceiling plate that extends generally perpendicular to the studs and parallel with the wall plate. A weather resistive barrier formed of material such as asphalt impregnated paper, plastic sheeting, building wrap or similar product may be attached to exterior facing edges of the wall studs, extending from stud to stud and from floor plate to ceiling plate. The weather resistive barrier inhibits flow of air and moisture through any gaps that may exist in the wall assembly.
Sheathing formed of materials such as, but not limited to, plywood, oriented strand board (OSB), wafer board, metallic sheeting, lapboard, gypsum sheathing and the like, may be fastened to the outward facing edges of the wall studs outward of the weather resistive barrier. The sheathing also typically extends from wall stud to wall stud and from the wall plate to the ceiling plate. The sheathing may provide the exterior surface of the structure or may itself be covered with another exterior cladding, exterior covering or exterior coating.
Services such as plumbing, electrical, tele-communications and the like may be provided for by forming generally horizontally aligned holes in the studs and placing conduit, or the like, through the horizontally aligned holes. Thereafter, wiring, pipes and the like may be threaded into and through the conduit or directly through the generally horizontally aligned holes.
Commonly, interior insulation is installed directly against interior facing surface of the weather resistive barrier in the spaces between the wall studs extending from the floor plate to the ceiling plate. The insulation may be of various forms including fiberglass batting, mineral wool, recycled paper, cellulose or the like. The object is to “fill” the space between the wall studs extending from the floor plate to the ceiling plate to limit thermal transfer from the interior of the structure wall to the exterior of the structure wall, and visa versa depending upon the structure's interior operating conditions and the outside climate.
A vapor barrier such as plastic sheeting or the like may be attached to the interior facing edges of the wall studs extending from wall stud to wall stud and from the ceiling plate to the floor plate enclosing the insulation between the wall studs and between the inner vapor barrier and outer weather resistive barrier.
Interior sheathing, such as drywall, gypsum board, paneling or the like is attached to the inward facing edge portions of the wall studs, the floor plate and the ceiling plate and access holes are cut in the interior sheathing to provide access to the electrical boxes, plumbing fittings and the like.
One drawback to such wall assemblies and framing methods is that such methods create thermal bridges in the structure's walls which decrease the effectiveness of the insulation and allows thermal energy to be conducted through the wall assembly from the inside to the outside, and from the outside to the inside depending upon the outside temperatures and the inside operating conditions.
Although insulation is provided between the wall studs between the exterior sheathing and the interior sheathing, the studs themselves provide little insulative value and walls formed by such methods are not thermally efficient because thermal transfer occurs through the wall studs which act as “thermal bridges”. When metal wall studs are used, such as those commonly used in commercial construction, the effectiveness of insulation between the metal wall studs may be reduced by more than fifty percent (50%).
For example, a wall assembly having exterior OSB sheathing and interior gypsum board sheathing supported by plural parallel spaced apart 2″×6″ wood wall studs therebetween and having T-21 rated fiberglass batting type insulation filling the spaces between the wood wall studs has an effective R-rating of approximately R-18 due to the thermal transfer through the wood wall studs. If the same wall assembly is constructed using steel wall studs between the exterior OSB cladding and the interior gypsum board sheathing the effective R-value drops to approximately R-8 because of the thermal loss through the steel wall studs.
Even when additional layers of thermal insulation are placed on the exterior of a structure, (adjacent to the exterior facing surface of the exterior cladding) the insulative effectiveness of such additional insulation is reduced by the common practice of attaching exterior cladding directly to the outward facing surface of the additional insulation with metal attachment means or framing elements that penetrate through the insulation thereunder to engage with the underlying wall studs to provide support for the exterior cladding.
Attaching additional insulation to the exterior of a structure is also known to cause condensation within the wall assembly, which occurs when moisture-laden air comes into contact with a surface having a temperature below the dew-point temperature of the moisture-laden air. In a wall assembly, condensation usually occurs during the cold weather months on the interior facing surface of the exterior cladding when warm moisture laden air from the interior of the structure penetrates the wall assembly and contacts, the cold interior facing surface of the exterior cladding. In warm weather months, the condensation usually forms on the exterior facing surface of the insulation by warm air penetrating the wall from the outside and contacting the cooler exterior facing surface of the insulation which can lead to moisture saturation of the insulation which degrades the effectiveness of the insulation. Without proper design and engineering, attaching insulation directly to the exterior of a structure can be ineffective and can even be detrimental to the useful life of the wall assembly as condensation can lead to rod, no, insect infestation and diminished insulative effectiveness.
Another drawback to such construction methods is the limited number of options for cladding the exterior of a light-frame structure. Although some exterior claddings are available, such as lap board, metal siding, paneling and the like, such cladding is typically limited to light-weight coverings that can be supported by hanger-type wall attachments. Cladding exterior walls with heavy materials such as brick, stone and the like has previously been difficult because the weight of such coverings must be supported by the wall attachments. Overcoming this difficulty leads to additional costs and expenses for larger foundations for vertical support, stronger beams for horizontal support and additional labor costs.
A further drawback to such construction methods is the limited ability to refurbish existing structures by changing the exterior. Generally, when an existing structure is “re-clad” the options available are limited to replacing the existing cladding, or fastening a light weight cladding over the top of the existing cladding. Unfortunately, at times this is not feasible because the existing cladding is too deteriorated to allow stable attachment of the new cladding system. Further, in some instances the vertical “plumbness” or planar nature of an exterior wall might be so poor that it is not feasible or practical to attach a new exterior cladding to the existing structure. Finally, attaching a new exterior cladding has the ability to alter the building's “footprint” sufficiently to cause property line set-back problems by extending the building's walls outwardly.
Evolving construction standards with increased emphasis on energy efficiency, “being green” and limiting greenhouse gas emissions have required construction methods and techniques to likewise change to focus on the energy efficiency of structures. One way to increase the energy efficiency of a structure is to add insulation to the structure walls. Another is to minimize, or if possible eliminate thermal bridges that allow energy loss. A third is to improve moisture management which improves durability and thermal performance of the wall assembly. An even more effective solution is to do all three; add insulation to the structure while effectively managing moisture and eliminating and minimizing thermal bridges. The combination of these efforts is known as “continuous insulation” which is defined in various building codes, such as, but not limited to, ASHREA 90.1 as insulation that is uninterrupted by framing members, except fasteners (screws, nails) and is installed either inboard or outboard of the wall.
The precise definition of “Continuous Insulation” as set forth in the proposed Seattle Energy Code of 29 Apr. 2010 with which Applicants are most familiar, defines continuous insulation as follows:                CONTINUOUS INSULATION (C.I): Insulation that is continuous across all structural members without thermal bridges other than fasteners (i.e., screws and nails) and service openings. It is installed on the interior or exterior or is integral to any opaque surface of the building envelope. Insulation installed between metal studs, z-girts, z-channels, shelf angles, or insulation with penetrations by brick ties and offset brackets, or any other similar framing is not considered continuous insulation, regardless of whether the metal is continuous or occasionally discontinuous or has thermal break material.        
What is needed is a system that allows exterior cladding to be installed on new structures and onto existing structures, and allows the walls to be insulated having a high degree of effective thermal insulation while minimizing or eliminating thermal bridges and moisture management problems. The system must accommodate a variety of exterior claddings and must allow the structure to be provided with a new appearance, including an appearance of being constructed of masonry, stone or the like. The system must comply with evolving construction standards including the new ASHRE 90.1 standards, including the standards for continuous installation. The system must be economical and efficient and provide sufficient flexibility and structural integrity to allow a user to clad the exterior of a structure as desired and simultaneously preserve the desirable features of known light frame construction methods and systems.
Our system overcomes various drawbacks of known construction apparatus, methods and techniques by providing an improved modular system that preserves user flexibility in the exterior cladding of a structure and maximizes the insulative capabilities by providing a continuously insulated structure having no or minimal thermal bridges that allow thermal energy loss.
Our system provides unique MFI-brackets that are attached to the underlying structure in a manner that the MFI-brackets are thermally isolated from the underlying structure to prevent creation of thermal bridges. The configuration of the MFI-brackets secures nonflammable/noncombustible insulation adjacent to the structure and provides a support for exterior cladding which may be either directly or indirectly mounted thereto.
An exterior cladding supporting system fastened to outward end portions of the MFI-brackets provides a vertical rail or horizontal rail upon which exterior cladding may be releasably secured. A desired exterior cladding may be fastened to exterior facing portions of the vertical rails and/or horizontal rails. Corner elements carrying complimentary sections of the desired exterior cladding are supported by the system at the structure corners.
A rain screen between an Interior facing surface of the exterior cladding and the exterior facing surface of the insulation provides a pressure equalized drain cavity that prevents moisture from passing from the exterior into the wall assembly, reduces condensation, and properly manages moisture. The pressure equalized drain cavity is configured to comply with fire standards to prevent formation of a “chimney” between the Interior facing surface of the exterior wall cladding and the exterior facing surface of the insulation.
Thermal isolators reduce thermal transfer between interconnecting elements by preventing metal to metal connections and the MFI-brackets provide a tapered down “bottle neck” that further reduces thermal transfer between the exterior cladding and the underlying structure and maximizes the effectiveness of the insulation.
Spacers optionally positioned between the thermal isolators and a wall assembly provide a means to adjust and repair the vertical plumbness and planar configuration of a wall assembly.
Our system increases the “effective R Value” of structures by providing a more energy efficient wall structure that loses less heat through thermal conduction through the wall structure.
Our system reduces moisture condensation within the wall assembly effectively manages moisture and minimizes energy losses related to thermal bridging.
Our system meets and exceeds evolving and changing building codes and regulations, such as but not limited to ASHRAE 90.1 standards which are the baseline energy efficiency guidelines used worldwide for promotion of energy efficiency, energy conservation and “greenness”.
Our system allows the exterior of a structure to be clad in a material that has the appearance and texture of masonry, stone and the like, without the weight of such construction and without the required foundation and other underlying support structures and construction costs that would be necessary to support construction with such heavy materials.
Our invention does not reside in any one of the identified features individually, but rather in the synergistic combination of all of its structures, which give rise to the functions necessarily flowing therefrom as hereinafter specified and claimed.